The present invention relates to an image data transformation apparatus and an image entry apparatus, and in particular, to an image data transformation apparatus for transforming multi-value color image data into binary image data and an image entry apparatus for reading a document to store binary image data thereof.
Conventionally, there have been commonly known an image filing system and a facsimile apparatus in which multi-value image data having multiple values is read by a scanner to be converted into binary image data, thereby accumulating and/or transmitting the resultant binary data.
In a case of a printed matter (to be called a monochrome character document with monochrome meaning a single color) in which black letters are printed on a sheet of white paper, the multi-value image data is constituted with data representing brightness or darkness not including any intermediate gradation or tone. In the transformation of the data, a check is made to decide whether or not the data of each pixel has a value of light intensity higher than a predetermined threshold value, thereby producing binary image data associated therewith.
Moreover, for example, when processing a monochrome photograph (to be called a monochrome photograph document), the multi-value image data is represented as light intensity data representing brightness and darkness of associated pixels and including intermediate gradation or tone levels. Consequently, there is employed a method such as a dithering method to convert the multi-value image data into binary image data.
In addition, for example, in a case where the transformation is accomplished on a printed matter (to be called a multi-color character document with multi-color meaning a plurality of colors but not full-color) in which, for example, black and red characters are printed on a sheet of white paper, the multi-value image data is constituted with light intensity data not including any intermediate gradation level in which the black characters are not discriminated from the red characters and with light intensity data which not including any intermediate gradation level which relates only to red character portions. Consequently, a check is made to decide whether or not the data of each pixel has a value of light intensity higher than a predetermined threshold value so as to transform the multi-value data into binary image data associated with only red character portions and binary image data in which the black and red characters are not discriminated from each other.
Furthermore, for example, in a case of a color photograph (a document including a color photograph is called a full-color document with color meaning full-color, namely all colors in the color spectrum), multi-value image data is constituted with light intensity data having intermediate tones only related to red portions, light intensity data having intermediate tones only related to green portions, and light intensity data having intermediate tones only related to blue portions. In consequence, the multi-value image data is converted, for example, by a dithering method into binary image data groups related only to red, green, and blue portions, respectively.
As above, the transformation method of transforming the multi-value data into binary data varies depending on the kinds or types of document. Consequently, prior to the read operation of the scanner for reading the document, it has been a common practice that the operator decides the kind of the objective document to input the document kind to the image filing system and/or the facsimile apparatus.
In the prior art, as described above, the operator determines the type of the objective document to specify the kind of multi-value image data and a method of converting the multi-value image into binary image data, which consequently leads to problems that the operations are complicated and the processing speed is decreased.